The following U.S. applications and patents are related to the subject matter of the present invention:                1. US Patent Application Serial No.: US 2003/0172182 A1, 11 Sep. 2003, “Multipath Content Distribution Aggregation”;        2. U.S. patent application Ser. No. 09/784,948, 15 Feb. 2011, “Paging During Media Loading”;        3. U.S. patent application Ser. No. 09/784,843, 15 Feb. 2011, “Programming Content Distribution”;        4. U.S. patent application Ser. No. 09/784,843, 15 Feb. 2011, “Distributed Storage of Audio/Video Content (the Distributed Storage Application)”;        5. U.S. patent application Ser. No. 09/784,843, 15 Feb. 2001, “Broadcast Message Management (the Broadcast Message Management Application)”.        6. US Patent Application Serial No. 2006/0181472 A1, 17 Aug. 2006, “Multiple Beam Feed Assembly”;        7. U.S. Pat. No. 7,202,833 B2, 10 Apr. 2007, “Thi-Head Kakuka Feed For Single Offset Dish Antenna”;        8. US Patent Publication No. US 2010/0022238 A1, 18 Jan. 2010, “Signal Transmission Mechanism With Diversity Gain in Satellite Communication Network”;        9. U.S. Pat. No. 6,442,385 B1, 27 Aug. 2002, “Method and Apparatus For Selectively Operating Satellites In Tundra Orbits to Reduce Received Buffering Requirements for Time Diversity Signals”,        10. U.S. Pat. No. 7,711,335 B2, 4 May 2010, “Digital Satellite Receiver and Method for Switching Among Multiple Receiver Antennas Using Diversity Circuitry”;        
Each of the above-listed ten (10) U.S. applications and patents is incorporated herein by reference.
The present invention in general concerns a geostationary satellite communication network using a hub network and a very small aperture terminal (VSAT). It is particularly directed to a geostationary satellite communication system (“satellite”) carrying data and Internet traffic on typical Fixed Satellite Services (FSS) bands (such as C, Ku, and Ka) with a single remote antenna dish and router.
Conventionally, a satellite communication network uses a network hub and a remote VSAT (or “Remote Terminal”) including a satellite dish, a feed, a low noise amplifier (LNA) or a low noise block down converter (LNB), a modulator/demodulator (modem), and a router. Each system uses a single dish, a single feed, an LNB, a modulator and a router, unique for each FSS band, namely, C-, Ku-, or Ka-Band in which its data throughput is limited for each band capacity. Higher spectrum provides higher data throughput due to higher availability of the spectrum. However, in a satellite link, the use of a higher spectrum suffers from the attendant problem of a higher probability of link degradation due to weather variations. On the other hand, a lower spectrum provides lower data throughput, but offers better link robustness. A multiple feed system (the feeds, the LNA or LNBs, and the radio frequency transmissions) in a single dish is a known system. This know system has been widely used for direct to home (DTH) applications, for receiving content from more than one Broadcast Satellite Services (BSS) network in a single spectrum (for example C- or Ku or Ka-Band) or multi spectrum (for example C- and Ku-Band).
The system according to the present invention discovered that it is possible to put multiple FSS networks (for example C-, Ku-, or Ka-Band) in a single dish and router that allow seamless transition among networks for the purpose of throughput maximization for the end users.
The object of the present invention is to increase data throughput for users within the coverage of multi spectrum FSS, when there is a possibility of using a higher spectrum (for example Ku- or Ka-Band) while maintaining the default throughput on a lower spectrum (for example C-Band).
The fact is, some geographical regions are able to operate in a lower spectrum (C-Band) with high service availability, and in higher spectrums (Ku- and Ka-Band) but with lower service availability. Lower service availability (or “lower availability”) on higher spectrum motivates satellite communication network operators in some parts of the geographical regions to operate only in the lower spectrum. This is unfortunate because the use of higher spectrum in the same geographical location under certain conditions gives higher data throughput albeit with lower availability. However, the present invention recognizes that lower availability “does not have to mean zero availability”.
Focusing on the economics of “does not mean have to mean zero availability” creates a possibility for users to maximize throughput on the higher spectrums on a statistical basis. Whenever possible, users will obtain higher throughput using a higher spectrum, and when the weather condition does not permit a desirable link margin for a sufficient user experience, then the system will seamlessly select the lower spectrum in their receiver system, i.e., a spectrum that offers lower throughput but a more robust link. The system according to an exemplary embodiment does this without the loss of the communication link during the transition between spectrums.
The lower throughput with a more robust link is defined as the “Default Throughput”. The satellite communication link that provides the Default Throughput is defined as the “Default Link.” The condition when only the Default Link can be established is defined as the “Default Condition”.
The higher throughput with less robust links is defined as the “Variable Throughput”. The satellite communication links that provide the Variable Throughput are defined as the “Variable Links”. The establishment of Variable Links is possible when the satellite transmission parameters allow the closure of the link with sufficient margin as determined by the service operator. The condition when the Default Link and the Variable Links can be established is defined as the “Advantageous Condition”.
When the Default Condition occurs, the user will obtain the Default Throughput on the Default Link. When the Advantageous Condition occurs, the user will obtain the Variable Link at least most of the time. Under the Advantageous Condition, the user will experience higher data speed when, for example, browsing the Internet or downloading/uploading data.
The process of switching between the Default to Variable Links, is transparent to the user. The desired link margin for each link is determined by the communication parameters (e.g., the modulation scheme, the satellite parameters, the hub parameters, the remote terminal parameters, and the geographical location, such as latitude and longitude) and stored in the modem.
This approach according to an exemplary embodiment of the invention is likely to be more and more desirable as users download larger amounts of data, such as movies or videos, use transfer control protocol/internet protocol (TCP/IP) over satellite, multiple spectrum satellite payload becomes more common, and TCP/IP allows more tolerant statistically variable throughput. Higher throughput spectrums (Ku- and Ka-Band) therefore will remain an advantage even for users in high precipitation areas, provided that users always have the guaranteed fall back services set by either C- or Ku-Band systems in a single product.